Motor vehicles – Special wheel base – Rider propulsion with additional source of power – e.g.,...
Reexamination Certificate
1999-12-06
2001-09-11
Dickson, Paul N. (Department: 3618)
Motor vehicles
Special wheel base
Rider propulsion with additional source of power, e.g.,...
C180S220000, C180S065510
Reexamination Certificate
active
06286616
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a hybrid propulsion system for a wheel-driven vehicle with an electric motor, which has two propulsion sources.
2. Description of Prior Art
Auxiliary electrical propulsion systems for vehicles powered by a rider, such as bicycles, tricycles and wheelchairs, have been known for some time.
Propulsion by an auxiliary electric motor is common to all these known vehicles, wherein the motor drives the driven wheel in parallel with the muscle power of the rider. This means that both sources of propulsion act in parallel to provide propulsion, so that their driving torque is added together.
As a result, the two sources of propulsion, the electric motor and the muscle power, act on the same driven wheel. The rpm of the two sources of propulsion are therefore coupled.
An increase in the rpm of the one source of propulsion does not necessarily result in a noticeable increase in the speed of movement. Instead, the other source of propulsion is relieved by this, until at the end its power output drops to zero.
It is possible to remedy this cause superficially by the use of a free-wheeling device, overriding clutches and the like.
It is thus possible to ride, for example, a bicycle with an auxiliary electrical propulsion system at higher speeds than the speed based on the maximum rpm of the motor, without the electric motor acting as a brake. However, it is the nature of the free-wheeling device, or respectively the overriding clutch, that the electric motor no longer provides a propulsive output for movement.
Therefore an increased use of the muscle power of the rider does not cause an appreciable increase in riding speed, but only a relief on the electric motor. With riders who like to move, this leaves an unsatisfied feeling, since they are used to experience an increase in riding speed as a result of an increase in muscle power, even on a non-motorized bicycle.
Frequent shifting is an unpleasant fact for most riders, which reduces the pleasure of riding. By none of the known gear-shifting methods, neither a chain changer nor a hub gearshift, is this unpleasant fact satisfactorily resolved.
Furthermore, in connection with the known electrically driven bicycles it is necessary for the two sources of propulsion, the electrical propulsion system and the muscle power, to operate at the same rotational speed. This means that, for example, an increase in the rotations per minute (rpm) of the electric propulsion system, for increasing the riding speed, is unavoidably connected with an increase in the rpm of the muscle-powered propulsion system. In the case of a bicycle with an auxiliary electric propulsion system this means an increase in the pedaling frequency of the rider. However, ordinary riders are only comfortable within a very narrow range of the pedaling frequency. This range normally lies between 50 and 60 revolutions per minute. It is of course possible to even this out within a defined range by means of known bicycle gearshift devices, for example a chain changer or a hub gearshift. But this means that the rider must operate the gearshift continuously.
SUMMARY OF THE INVENTION
This invention is based on eliminating the above mentioned disadvantages to the greatest possible extent by creating a sporty bicycle with an auxiliary motor which converts each additional employment of the muscle power of the rider into an increased riding speed in each operational state, and in this way lends a very sporty feel to the ride. It is also intended to relieve the rider of the manual operation of a chain changer or a hub gearshift. It is intended to make riding at any speed possible, while the pedaling frequency remains the same.
The two propulsion sources should be able to provide propulsion at any desired rpm, completely independently of each other.
In accordance with this invention, this is achieved by means of a hybrid propulsion system with the characteristics set forth in this specification and in the claims. Thus, an electric motor, a so-called wheel hub motor, is used, which directly drives each driven wheel.
With the arrangement in accordance with this invention, the two propulsion sources, the electric motor and the muscle power, can provide propulsion at any, completely different rpm. For example, the electric motor can provide propulsion at very high rpm, while the muscle power aids in the propulsion at very low rpm, for example fast riding along with comfortable pedaling, or exactly vice versa, rapid, sporty riding along with low current use. The output of both propulsion sources is completely converted into movement energy and increased riding speed. Each increase in the rpm of one of the two propulsion sources results in an increase of the riding speed, because the rpm of the two propulsion sources are added, or respectively superimposed on each other.
In the case of a bicycle with an auxiliary motor, an increase in riding speed occurs with each increase in the pedaling output of the rider. This means that a sporty rider can ride a bicycle, in accordance with this invention, arbitrarily fast. No restricting limits are set for him by the maximum rpm of the electric motor.
The riding speed of a vehicle in accordance with this invention can be arbitrarily changed by an appropriate control of the rpm of the electric motor as a function of the pedaling frequency, even though the pedaling frequency of the rider remains constant. This can be regulated by an appropriate electronic device in such a way that the pedaling speed is kept constant over a wide range of different riding conditions, and the operation of a bicycle gearshift is omitted.
The muscle-powered propulsion system can be selectively engaged with the stator or the rotor of the electric motor by means of any coupling device, for example a dog coupling or ratchets known from the hub gearshift. Thus, two completely different types of propulsion are available to the rider, one for slow speeds on a hill, which provides parallel propulsion and adds the torques together, and one for faster riding on level ground, which adds the rpm together.
The propulsion system in accordance with this invention is used in various fields. It is preferably employed in bicycle-like vehicles.
Direct driving, brushless d.c. motors are most frequently used. They can be employed with particular advantage at the relatively low rpm. However, direct-drive motors with commutation by means of brushes are also conceivable. In these cases the electronic control device is preferably housed outside of the hub, or at least on a non-moving element inside the hub. It is thus necessary to attach only two contact rings for transmitting the positive and the negative poles.
In connection with multi-wheeled hybrid vehicles driven by muscle power and an electric motor, the propulsion system in accordance with this invention can be placed as an intermediate shaft in the drive train between the crank and the rear wheel. With such an arrangement it is possible to also use electric motors with less torque, such as conventional, mechanically commutated d.c. motors, wherein the stator, generally embodied as a housing, is driven by muscle power. The power take-off rpm generated by the muscle power and the electric propulsion system can be picked up at the power take-off side and can be transferred by chains or a toothed belt transmission to the driving wheel.
On a bicycle with an auxiliary electrical propulsion system, the entire propulsion unit is preferably housed in the rear wheel. Here, the stator of the electric motor as well as the toothed rings driven by muscle power are rotatably seated on a central shaft. The rotor of the electric motor is designed as the housing of the wheel hub enclosing the stator, which is connected with the rim by commercially available spokes. The stator, which is also rotatably seated on the central shaft, is housed inside the rotor designed as the housing of the hub. The housing of the wheel hub used as the rotor is preferably made of two parts, for the simple assembl
Dickson Paul N.
Lerner Avraham H.
Pauley Petersen Kinne & Fejer
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